BACKGRoUND:Endothelial basal medium is mainly used to culture endothelial progenitor cells.Studies on mesenchymal stem cells (MSCs) cultured in this medium are few. OBJECTIVE:To compare the outcome of MSCs cultured in different mediums including endothelial basal medium. DESiGN.TIME AND SETTING:The control eell experiment was performed at the Muniopal Key Laboratory of Xinhua Hospital of Shanghai.China from September 2005 to May 2006. MATERIALS:Eight pregnant mongrel dogs were selected to obtain umbilical cord blood for isolation and culture of stem cells. Endothelial eell basal medium and endothelial cell medium were bought from Clonetics.USA.Mouse anti-CDlla monoclonal andbody,mouse anti-CDllb monoclonal antibody.mouse anti-CD29 monoclenal antibody and mouse anti-CD7l monoclonal antibody Were purchased from Antibody diagnostica,USA.Mouse anti-CD34 monoclonal antibody was obtained from Lab Vision Corporation.USA.METHODS:Umbilical cord blood stem cells were divided into four groups.Umbilical cord blood steTn cells in the group A were incubated in the endothellal basal medium.Umbilical cord blood steHl cells in the group B were incubated in the endothelial basal medium containing microvascular endothelial cells in a 6-well plate.Umbilical cord blood stem cells in the group C were incubated in the endothelial basal medium containing endotheliaI medium in a 6-well plate coated with fibronectin.Umbilical cord blood stelrn cells in the group D were incubated in the endothelial basal medium containing endothelial medium in a 25 cm2 ctdturing flask.MAIN OUTCOME MEASURES:Cell morphology and population doublings were observed.CDlla,CDllb,CD34,CD29 and CD71 expression was detected by immunohistochemistry. RESULTS:Fibroblast-like cells were measured in each group.The celIs grew badly in morphology and proliferated slowly in the group A,while cells proliferated rapidlyinthe group B.The cell clones were instable and inclined to aging in the group C,with a new cell clone was found.The cells in the group D were similar to those in the group C.Surface antigens detected by immunohistochemistry showed CDlla(-),CDllb(-),CD34(-),CD29(+)and CD7l(+). CONCLUSION:MSCs witll well growth and rapid proliferation can be detected in the endothelial basal medium containing endothellal medium in an intact 6-well plate.The outcome is bad in fibronectm-coated plate or 25 cm2 culture flask.

BACKGROUND: Umbilical cord blood-mesenchymal stem cells (UCB-MSCs) following differentiation into cardiomyocytes were transplanted into ischemic myocardium. The transplanted cells can build connection with host cells and repair the infarct myocardium. OBJECTIVE: To detect the cell-cell junction after transplantation of the cardiac-like cell derived from the canine umbilical cord blood stem cells. DESIGN, TIME AND SETTING: A randomized controlled animal study was performed from July 2006 to October 2007 at the Animal Experimental Center of Xinhua Hospital Affiliated to School of Medicine, Shanghai Jiao Tong University. MATERIALS: A total of 2 full-term pregnant canines were used for isolation of UCB-MSCs. A total of 36 adult mongrel canines were divided into cell transplantation group and model control group (n=18) according to the rule of random digits table. METHODS: The MSCs at passage 4 were transfected by Laz-Z. After 3-day culture, MSCs were induced by 10 μmol/L 5-azacytidine (5-aza). The canine models of myocardium infarction were established following 3 weeks of culture. 2 mL (1 ×107)MSCs were transplanted into dogs with acute myocardium infarction by coronary artery infusion and local injection in cell transplantation group. An equal volume of saline was used in the model control group. The specimens were harvested and detected at 2, 4 and 8 weeks, respectively. Cell junction was determined using immunohistochemistry. MAIN OUTCOME MEASURES: The following parameters were measured: gene trensfection, myogenic induction and differentiation results of UCB-MSCs; junction of transplanted cells and host cardiomyocytes. RESULTS: Following 72 hours of transfaction, mass of cells expressed LacZ gene, synthetized galactosidase, and stained blue using X-gal staining. Following 3 weeks of 5-aza induction, the antigen a-Actin, Desmin and Connexin43 were all been positively expressed, but before induction they were all negative. From the myocardial section of 8 weeks after transplantation, the junction was formed between the transplanted cells and the host myocardium as formed between the transplanted cells. In the junction, green-fluorescence positive expression of cadherin and connexin43 could be seen. However, in the model control group, only cadherin and connexin43 expressed positively, but the transplanted UCB-MSCs with red fluorescence could not been observed. CONCLUSION: The UCB-MSCs is able to differentiate into cardiac-like cell in vitro and form cell-cell junction in vivo to communicate with surrounding cells.